I read that in a few tests, baking soda was actually the best at removing some of the main pesticides on fruits/vegetables. I wonder if this is the same for other things like plants. It would make a simple and safe cleaner.
I saw a similar article as this(saying the same thing basically).
If they were all water based, they wouldn't hold up that well in the rain, no?
They are water based, they are not oil or alcohol based. Maybe they are like "salts" and once the water dries, its harder to wash off with cold water? And fruits at least are coated with a think layer of wax stuff, to prevent rotting etc, its not a pesticide and is edible. But if you want to remove it, it comes off with warm water.
Like i said, your method may work great. It may break down any residue much faster vs warm water. My main concern is its ability to remove/damage the protective layer on the leaves. In the "food" case, you will be eating it within the week else it goes rotten. In the plant case, you want it to live forever.
You could always just get a "stunt" plant, and wash it with soda once a week or something, and see if it stays good.